Working on the parser

If there's a problem parsing, you will want to edit the grammar under
lib/parser/pbxproj.pegjs. You can test it online with the PEGjs online thingy
at http://pegjs.majda.cz/online - I have had some mixed results though.

Tests under the test/parser directory will compile the parser from the
grammar. Other tests will use the prebuilt parser (lib/parser/pbxproj.js).